Introduction to Git
Local Version Control Systems
Many people’s version-control method of choice is to copy files into another directory (perhaps a time-stamped directory, if they’re clever). This approach is very common because it is so simple, but it is also incredibly error prone. It is easy to forget which directory you’re in and accidentally write to the wrong file or copy over files you don’t mean to.
To deal with this issue, programmers long ago developed local VCSs that had a simple database that kept all the changes to files under revision control.
Centralized Version Control Systems
Clients have a single central copy of a project on a server.
The problem is if the hard disk the central database is on becomes corrupted, and proper backups haven’t been kept, programmer loses absolutely everything — the entire history of the project except whatever single snapshots people happen to have on their local machines.
Examples of such system are SVN (Subversion), CVS, Perforce
Centralized Version Control Systems
Delta-based version control
Distributed Version Control Systems
With distributed version control systems (DVCS), you don’t rely on a central server to store all the versions of a project’s files. Instead, you clone a copy of a repository locally so you have the full history of the project.
Thus, if any server dies, and these systems were collaborating via that server, any of the client repositories can be copied back up to the server to restore it. In DVCS most operations are executed locally!
Two common distributed version control systems are Git and Mercurial.
What is Git?
Git is a free and open source distributed version control system designed to handle everything from small to very large projects with speed and efficiency
What is Git?
Git thinks about data more like stream of snapshots
Recording changes to the git repository
- Create new file or edit existing file or files in the Working Directory;
- Stage changes (add to index);
- Commit (only added to index changes)
You can’t commit changes that are not staged
Recording changes to the git repository
- Each file in your working directory can be in one of two states: tracked or untracked;
- Tracked files can be unmodified, modified.